I have bad news and worse news. The money withheld will not be enough to pay the taxes really due. You have a deposit in the amount withheld at the IRS, if you will. However, taxes on early withdrawal from a retirement account are also assessed a penalty of 10%.
Now the worse news. If you live in a state with an income tax, you may be assessed state income tax. Some states, like Wisconsin, add another penalty for early distributions from a retirement account.
It is common to pay over half the retirement distribution in tax and penalty. I see it all too often.
Another note: Money in your retirement account is exempt from bankrupcy. Taking the money out kills your retirement and you took protected money and threw it away.
My advice: Never take money from a retirement account until retirement.